Occurs 1-2 per
1000 births. This birth defect results from incomplete closure
of the neural tube. This usually affects the nerves at the level of the defect. The
severity depends on the location and
size of the defect, as well as the extent of nerve root
involvement. Hydrocephalus requiring a shunt
often complicates spina bifida.

Cleft lip/palate

A defect of the
lip and/or palate. Varies with type and severity.

Cystic fibrosis

One of the most
common genetic conditions. It causes chronic lung and intestinal
problems, poor
weight gain and other symptoms, usually beginning in early
childhood. Although treatment for cystic
fibrosis has improved, life span and quality of life remain
limited.

Tay-Sachs Disease

Occurs mainly
in Ashkenazi Jews (ones of Eastern European descent). It is a
disorder in which
infants, who can appear normal at birth, develop degenerative
neurologic problems and generally die
by the age of five. No treatments are currently available.

Bloom syndrome results in individuals having many abnormalities
including an increased susceptibility
to cancer and leukemia. Some individuals with Bloom syndrome
also have mental retardation. One in
100 Ashkenazi Jewish individuals is a carrier for Bloom
syndrome.

Canavan disease is caused by the lack of an enzyme in the body
called aspartoacylase (ASPA). Canavan disease may cause
brain damage, a large head, tremors, blindness, feeding
difficulties, poor weight gain, and problems with swallowing.
An estimated one in 40 Ashkenazi Jews is a carrier for
Canavan disease.

Familial dysautonomia (FD) is an inherited disorder leading to
problems with swallowing,
temperature regulation, blood pressure regulation, feeding, and
sensation to pain. An estimated one
in 30 Ashkenazi Jews is a carrier for FD.

Fanconi anemia in an inherited condition characterized by a
reduced production of all types of blood
cells. Individuals with Fanconi anemia have many abnormalities
including an increased risk for
cancer and leukemia. An estimated one in 89 Ashkenazi Jews is a
carrier for Fanconi anemia.

Gaucher disease is an inherited disorder caused by a change in
the gene responsible for making an
enzyme called glucocerebrosidase This can cause a wide range
of abnormalities including liver and
bone abnormalities. Type 1 Gaucher disease is the most common
genetic disorder among Jews. An
estimated one in 10 Ashkenazi Jews is a carrier for Gaucher
disease.

Niemann-Pick disease (Type A) is caused by the lack of a
substance called acid sphingomyelinase.
Individuals with Nieman-Pick have problems including
developmental delay, progressive spasticity,
blindness, an enlarged liver and/or spleen, and a "cherry-red
spot" in the eye. An estimated one in
100 Ashkenazi Jews is a carrier for Niemann-Pick disease.

Sickle cell disease

An inherited
disease of red blood cells which can cause attacks of pain,
damage to vital organs, risk of serious infections and can lead
to early death. Sickle cell disease affects the main protein
inside the red blood cells called hemoglobin. The disease occurs
when a person inherits one sickle cell gene from each parent or
a combination of one sickle cell gene plus one of several other
abnormal hemoglobin genes. One of the most serious complications
of sickle cell anemia is stroke, a bleed or blockage of blood
within the blood vessels of the brain. About 10 percent of
children with sickle cell anemia have a stroke, which can lead
to lasting disabilities, by age 20.
Most cases of sickle cell disease occur among African-Americans,
and Hispanics of Caribbean ancestry. About one in every 400
African-Americans has sickle cell disease. It also affects
people of Arabian, Greek, Maltese, Italian, Sardinian, Turkish
and Indian ancestry.

Thalassemia

Thalassemia
consists of a group of inherited diseases of the blood. About
100,000 babies worldwide are born with severe forms of the
disease each year. Thalassemia occurs most frequently in people
of Italian, Greek, Middle Eastern, Southern Asian and African
ancestry.

Thalassemia
includes a number of different forms of anemia (red blood cell
deficiency). The two main types are called alpha and beta
thalassemias, depending on which part of an oxygen-carrying
protein (called hemoglobin) is lacking in the red blood cells.
The most severe form of alpha thalassemia, which affects mainly
individuals of affects lacking in the red blood cells. The most
severe form of alpha results in affects mainly individuals of
Southeast Asian, Chinese and Filipino Southeast Asian, Chinese
and Filipino ancestry, milder forms of the results in fetal or
newborn death. Most individuals with alpha no effect on health.
milder forms of the disease, with varying degrees of anemia. Individuals with no effect on health.beta thalassemias have
variable symptoms ranging from very severe to having no effect
on health.results in fetal or newborn death. Most individuals
with alpha thalassemia have milder forms of the disease, with
varying degrees of anemia. Individuals with beta thalassemias
have variable symptoms ranging from very severe to having no
effect on health.

Thalassemia major, the most severe form, is also called Cooley's
anemia, named after the doctor who first described it in 1925.
Most children with t thalassemia major appear healthy at birth,
but during the first year or two of life they become pale,
listless and fussy, and have a poor appetite. They grow
slowly and often develop jaundice (yellowing of the skin). Without treatment, the spleen, liver, and heart soon become
greatly enlarged. Bones become thin and brittle; face bones
become distorted, and children with thalassemia often look
alike. Heart failure and infection are the leading causes of
death among children with untreated thalassemia major.

Thalassemia intermedia is a mild Cooley's anemia. Children with
thalassemia intermedia may develop some of the same
complications, although in most cases, the course of the disease
is mild for the first two decades of life.

Fragile X syndrome

The most common
inherited form of mental retardation, affecting about 1 in 4,000
males and 1 in
8,000 females (Down syndrome is the most common cause of mental
retardation, occurring in about
1:700 birth, but it is rarely inherited).

Fragile X syndrome
occurs in all racial and ethnic groups.
It is caused by an abnormality in a single gene of the "X"
chromosome. This is also one of the "sex"
chromosomes (females have 2 X chromosomes while males have one X
and one Y chromosome). The mutation- (called FMR-1) - was discovered in 1991 and it can
be tested for in families known
to be at risk. About one in 250 women in this country carries
the fragile X gene. A woman is
considered a carrier of fragile X syndrome if she has either a
pre-mutation (60 to 200 trinucleotide
repeats within her FMR-1 gene) or a full mutation (greater than
200 trinucleotide repeats within her
FMR-1 gene). A carrier of a pre-mutation generally has no
symptoms of fragile X syndrome, though
recent studies suggest that women who carry this pre-mutation
may be at increased risk of early
menopause (prior to age 40). Approximately one-third to one-half
of female carriers of a full
mutation will exhibit signs of fragile X syndrome, but are usually less severely affected than males
with full mutations. Because the genetics of fragile X syndrome
are complicated, a couple with a
family history of fragile X syndrome should consult a medical geneticist or a genetic counselor to
learn more about the risks of this disorder in their offspring.